The present invention relates to an apparatus and method for detecting an epilepsy seizure.
A brain wave is obtained by measuring a change in potential difference caused by a weak electrical activity of the brain by means of scalp electrodes or intracranial electrodes or the like, amplifying a measured signal, and expressing the amplified signal as a waveform. An epilepsy seizure means various signs and symptoms derived from excess discharge of neurons of the cerebral cortex.
An epilepsy seizure is detected as a sudden abnormal wave of a brain wave. Usually, a brain wave obtained by using scalp electrodes is used in the detection. However, a brain wave obtained by this method is susceptible to various kinds of noises. In an epilepsy seizure, a noise which largely affects a brain wave is an electromyogram which is induced with myotonia. An epilepsy seizure often involves a motor seizure and a body motion. Therefore, it often occurs that brain wave signals are covered by an electromyogram and an epilepsy seizure cannot be detected from a brain wave. Furthermore, it is often that an epilepsy seizure localized to the deep brain such as the medial-temporal lobe cannot be detected from a brain wave obtained by using scalp electrodes.
By contrast, a brain wave obtained by using intracranial electrodes is not affected by an electromyogram as compared to a brain wave obtained by using scalp electrodes, and therefore it is possible to record an electrical activity in the deep brain. However, an installation of intracranial electrodes requires a neurosurgical procedure, and hence is highly invasive. Moreover, there is a risk for complications. Therefore, such an installation imposes a heavy burden on the patient.
As a related-art method of detecting an epilepsy seizure without using a brain wave, there is a method in which the heart beat rate is measured by seconds, and an epilepsy seizure is detected by an appearance of a bradycardia following a tachycardia (refer to JP-T-2009-519803).
In the related-art method, an epilepsy seizure is detected based only on a change of the heart beat rate, and therefore there is a possibility that an event which is not an epilepsy seizure may be erroneously detected as an epilepsy seizure. Moreover, there is a further possibility that the sensitivity of detection of an epilepsy seizure cannot be improved.